Three experiments are starting to study dark energy, the most abundant stuff in the universe. But a theory has just been published purporting to show it does not exist

IN THE 1920s astronomers realised that the universe was running away from them. The farther off a galaxy was, the faster it retreated. Logically, this implied everything had once been in one place. That discovery, which led to the Big Bang theory, was the start of modern cosmology.

In 1998, however, a new generation of astronomers discovered that not only is the universe expanding, it is doing so at an ever faster clip. No one knows what is causing this accelerating expansion, but whatever it is has been given a name. It is known as dark energy, and even though its nature is mysterious, its effect is such that its quantity can be calculated. As far as can be determined, it makes up two-thirds of the mass (and therefore, E being equal to mc2, two-thirds of the energy) in the universe. It is thus, literally, a big deal. If you do not understand dark energy, you cannot truly understand reality.

Cosmologists are therefore keen to lighten their darkness about dark energy, and three new experiments—two based in Chile and the third in Hawaii—should help them do so. These experiments will look back almost to the beginning of the universe, and will measure the relationships between galaxies, and clusters of galaxies, in unprecedented detail. When they are done, though the nature of dark energy may remain unresolved, it should at least be clearer.

If, that is, it actually exists. For a core of cosmological refuseniks still do not believe in it. They do not deny the observations that led others to hypothesise dark energy, but they do deny the conclusion. For them, then, these experiments provide an opportunity to test alternative theories.

Darkness and dawn

The most advanced of the new experiments is the five-tonne, 570-megapixel Dark Energy Camera, which was installed last year at the Cerro Tololo Inter-American Observatory in Chile, 2,200 metres (7,200 feet) above sea level in the Atacama Desert. It is expected to open for business in a few weeks’ time, taking 400 one-gigabyte pictures of the sky each night, for 525 nights over five years.

This photographic marathon is part of the Dark Energy Survey (DES), a project led by Joshua Frieman of the University of Chicago. Dr Frieman’s plan is to scan an eighth of the sky, examining 100,000 galaxy clusters as he does so and measuring the distances to 300m individual galaxies within those clusters.

The reason for all this effort is that tracing the way the sizes and shapes of galactic clusters change over time allows each round of the battle between gravity and dark energy to be studied in detail. Gravity, which tends to slow down the expansion of the universe, causes clusters to become more compact. Dark energy, which tends to speed universal expansion up, causes clusters to spread out. The rate of contraction or expansion of clusters shows the relative strengths of the two forces. Dr Frieman and his colleagues cannot follow the changes in any given cluster since they see only a snapshot of its history. But looking at the differences between lots of clusters of various ages is the next best thing.

Previous observations have suggested that for more than half of the universe’s 13.7-billion-year life, gravity had the upper hand. Only about 6 billion years ago did dark energy overtake it. The DES hopes in particular to study the transitional period, by peering back as far as 10 billion years by the simple expedient of looking at clusters up to 10 billion light-years away.

The second of the new experiments, the Subaru Measurement of Images and Redshifts (SuMIRe), led by Hitoshi Murayama of the Kavli Institute for the Physics and Mathematics of the Universe, in Tokyo, is based on a mountain top in Hawaii. It will start collecting data next year, in a manner similar to the Dark Energy Camera, but better. Though it will look at only a tenth of the sky, rather than an eighth, it can see farther—13 billion light-years, rather than 10 billion. It also has more bells and whistles than the Dark Energy Camera; specifically, it has an integral spectrograph, for working out redshifts.

Redshifts are one of astronomy’s most important sources of information. They tell you how far away a galaxy is. They are caused by the Doppler effect, a phenomenon familiar on Earth as the change in pitch of a police-car or ambulance siren as the vehicle approaches and then recedes. Light, too, is subject to Doppler shifts, and the light from a receding object is thus redder (ie, of longer wavelength) than it otherwise would be. The faster the object is moving away, the redder it is. It was this that allowed those 1920s astronomers, led by Edwin Hubble, to work out that the universe is expanding. The Dark Energy Camera, which lacks a spectrograph, has to rely on other telescopes which do have them to make its redshift measurements for it. Having an integral spectrograph will thus give SuMIRe an advantage.

The third experiment, ACTPol (Atacama Cosmology Telescope Polarisation sensitive receiver), run by Lyman Page of Princeton University, is rather different. Instead of looking at light from galaxies, it will study microwaves from the cosmic microwave background (CMB). This was created around 380,000 years after the Big Bang, and thus preserves an imprint of what the early universe looked like.

ACTPol, too, is in Chile, on the peak of a mountain called Cerro Toco. Tests began on July 19th. Its purpose is to look at the CMB’s polarisation, any part of which will have been distorted in meaningful ways by the microwaves’ passage through intervening galaxies from their creation to their arrival on Earth. And from that, using a lot of statistical jiggery-pokery, a third estimate of the yo-yo effect of gravity and dark matter on galactic clusters should emerge.

If these three experiments work, and agree with one another, it will be a big step forward in understanding how the universe has evolved from an object smaller than an electron into the vastness seen today. Theoreticians will be able to plug the new data into their models of dark energy, and see what comes out. But others will be able to use the data too. And they may come to different conclusions.

Crazy enough to be correct?

Even as astronomers vie to explain the mystery of the expanding universe, some theorists are trying to explain it away. The most recent such attempt has just been published by Christof Wetterich, of the University of Heidelberg, in Germany. Not only does he not believe in dark energy, he does not believe the universe is expanding at all.

That, in the context of modern cosmology, is a pretty grave heresy. But Dr Wetterich’s latest paper, published on arXiv, an online repository, attempts to back it up.

In Dr Wetterich’s picture of the cosmos the redshift others attribute to expansion is, rather, the result of the universe putting on weight. If atoms weighed less in the past, he reasons, the light they emitted then would, in keeping with the laws of quantum mechanics, have been less energetic than the light they emit now. Since less energetic light has a longer wavelength, astronomers looking at it today would perceive it to be redshifted.

At first blush this sounds nuts. The idea that mass is constant is drilled into every budding high-school physicist. Abandoning it would hurt. But in exchange, Dr Wetterich’s proposal deals neatly with a big niggle in the Big Bang theory, namely coping with the point of infinite density at the beginning, called a singularity, which orthodox theories cannot explain.

Dr Wetterich’s model does not—yet—explain the shifts in the shapes of galactic clusters that the Dark Energy Camera, SuMIRe and ACTPol are seeking to clarify. But perhaps, one day, it could. Dr Wetterich is a well-respected physicist and his maths are not obviously wrong. Moreover, his theory does allow for a short period of rapid expansion, known as inflation, whose traces have already been seen in the CMB. Dr Wetterich, however, thinks this inflation did not happen just after the beginning of the universe (the consensus view), for he believes the universe had no beginning. Instead, a small static universe which had always existed turned into a large static one that always will exist—getting heavier and heavier as it does so. There was thus no singularity.

Probably, this theory is wrong. As Cliff Burgess of Perimeter Institute, a Canadian theoretical-physics centre, puts it, “The dark energy business very easily degenerates into something like a crowd of people who are each claiming to be Napoleon while asserting that all the other pretenders are clearly nutty.” But theories last only as long as they do not conflict with the data, and when the new experiments have finished there will be a lot more data for them to conflict with, and thus reveal who the real Napoleon actually is. Perhaps, therefore, the last word should go to Niels Bohr, one of the founders of quantum theory. He once said to a colleague, Wolfgang Pauli, “We are all agreed that your theory is crazy. The question that divides us is whether it is crazy enough to have a chance of being correct.”

Seamus Heaney is widely recognized as one of the major poets of the 20th century. A native of Northern Ireland, Heaney was raised in County Derry, and later lived for many years in Dublin. He was the author of over 20 volumes of poetry and criticism, and edited several widely used anthologies. He won the Nobel Prize for Literature in 1995 "for works of lyrical beauty and ethical depth, which exalt everyday miracles and the living past." Heaney taught at Harvard University (1985-2006) and served as the Oxford Professor of Poetry (1989-1994). He died in 2013.

Heaney has attracted a readership on several continents and has won prestigious literary awards and honors, including the Nobel Prize. As Blake Morrison noted in his work Seamus Heaney, the author is "that rare thing, a poet rated highly by critics and academics yet popular with 'the common reader.'" Part of Heaney's popularity stems from his subject matter—modern Northern Ireland, its farms and cities beset with civil strife, its natural culture and language overrun by English rule. The New York Review of Books essayist Richard Murphy described Heaney as "the poet who has shown the finest art in presenting a coherent vision of Ireland, past and present." Heaney's poetry is known for its aural beauty and finely-wrought textures. Often described as a regional poet, he is also a traditionalist who deliberately gestures back towards the “pre-modern” worlds of William Wordsworth and John Clare.

Heaney was born and raised in Castledawson, County Derry, Northern Ireland. The impact of his surroundings and the details of his upbringing on his work are immense. As a Catholic in Protestant Northern Ireland, Heaney once described himself in the New York Times Book Review as someone who "emerged from a hidden, a buried life and entered the realm of education." Eventually studying English at Queen’s University, Heaney was especially moved by artists who created poetry out of their local and native backgrounds—authors such as Ted Hughes, Patrick Kavanagh, and Robert Frost. Recalling his time in Belfast, Heaney once noted: "I learned that my local County Derry [childhood] experience, which I had considered archaic and irrelevant to 'the modern world' was to be trusted. They taught me that trust and helped me to articulate it." Heaney’s work has always been most concerned with the past, even his earliest poems of the 1960s. According to Morrison, a "general spirit of reverence toward the past helped Heaney resolve some of his awkwardness about being a writer: he could serve his own community by preserving in literature its customs and crafts, yet simultaneously gain access to a larger community of letters." Indeed, Heaney's earliest poetry collections— Death of a Naturalist (1966) and Door into the Dark (1969)—evoke "a hard, mainly rural life with rare exactness," according to critic and Parnassus contributor Michael Wood. Using descriptions of rural laborers and their tasks and contemplations of natural phenomena—filtered through childhood and adulthood—Heaney "makes you see, hear, smell, taste this life, which in his words is not provincial, but parochial; provincialism hints at the minor or the mediocre, but all parishes, rural or urban, are equal as communities of the human spirit," noted Newsweek correspondent Jack Kroll.

As a poet from Northern Ireland, Heaney used his work to reflect upon the "Troubles," the often-violent political struggles that plagued the country during Heaney’s young adulthood. The poet sought to weave the ongoing Irish troubles into a broader historical frame embracing the general human situation in the booksWintering Out (1973) and North (1975). While some reviewers criticized Heaney for being an apologist and mythologizer, Morrison suggested that Heaney would never reduce political situations to false simple clarity, and never thought his role should be as a political spokesman. The author "has written poems directly about the Troubles as well as elegies for friends and acquaintances who have died in them; he has tried to discover a historical framework in which to interpret the current unrest; and he has taken on the mantle of public spokesman, someone looked to for comment and guidance," noted Morrison. "Yet he has also shown signs of deeply resenting this role, defending the right of poets to be private and apolitical, and questioning the extent to which poetry, however 'committed,' can influence the course of history." In the New Boston Review, Shaun O'Connell contended that even Heaney's most overtly political poems contain depths that subtly alter their meanings. "Those who see Seamus Heaney as a symbol of hope in a troubled land are not, of course, wrong to do so," O'Connell stated, "though they may be missing much of the undercutting complexities of his poetry, the backwash of ironies which make him as bleak as he is bright."

Heaney’s first foray into the world of translation began with the Irish lyric poemBuile Suibhne. The work concerns an ancient king who, cursed by the church, is transformed into a mad bird-man and forced to wander in the harsh and inhospitable countryside. Heaney's translation of the epic was published as Sweeney Astray: A Version from the Irish (1984).New York Times Book Review contributor Brendan Kennelly deemed the poem "a balanced statement about a tragically unbalanced mind. One feels that this balance, urbanely sustained, is the product of a long, imaginative bond between Mr. Heaney and Sweeney." This bond is extended into Heaney's 1984 volume Station Island, where a series of poems titled "Sweeney Redivivus" take up Sweeney's voice once more. The poems reflect one of the book’s larger themes, the connections between personal choices, dramas and losses and larger, more universal forces such as history and language. In The Haw Lantern(1987)Heaney extends many of these preoccupations. W.S. DiPiero described Heaney's focus: "Whatever the occasion—childhood, farm life, politics and culture in Northern Ireland, other poets past and present—Heaney strikes time and again at the taproot of language, examining its genetic structures, trying to discover how it has served, in all its changes, as a culture bearer, a world to contain imaginations, at once a rhetorical weapon and nutriment of spirit. He writes of these matters with rare discrimination and resourcefulness, and a winning impatience with received wisdom."

With the publication of Selected Poems, 1966-1987 (1990) Heaney marked the beginning of a new direction in his career. Poetry contributor William Logancommented of this new direction, "The younger Heaney wrote like a man possessed by demons, even when those demons were very literary demons; the older Heaney seems to wonder, bemusedly, what sort of demon he has become himself." In Seeing Things (1991) Heaney demonstrates even more clearly this shift in perspective. Jefferson Hunter, reviewing the book for the Virginia Quarterly Review, maintained that collection takes a more spiritual, less concrete approach. "Words like 'spirit' and 'pure'… have never figured largely in Heaney's poetry," Hunter explained. However, in Seeing Things Heaney uses such words to "create a new distanced perspective and indeed a new mood" in which "'things beyond measure' or 'things in the offing' or 'the longed-for' can sometimes be sensed, if never directly seen." The Spirit Level (1996) continues to explore humanism, politics and nature.

Always respectfully received, Heaney’s later work, including his second collected poems, Opened Ground: Selected Poems, 1966-1996 (1998), has been lavishly praised. Reviewing Opened Ground for the New York Times Book Review, Edward Mendelson commented that the volume “eloquently confirms [Heaney’s] status as the most skillful and profound poet writing in English today." With Electric Light(2001), Heaney broadened his range of allusion and reference to Homer and Virgil, while continuing to make significant use of memory, elegy and the pastoral tradition. According to John Taylor in Poetry, Heaney "notably attempts, as an aging man, to re-experience childhood and early-adulthood perceptions in all their sensate fullness." Paul Mariani in America found Electric Light "a Janus-faced book, elegiac" and "heartbreaking even." Mariani noted in particular Heaney's frequent elegies to other poets and artists, and called Heaney "one of the handful writing today who has mastered that form as well."

Heaney’s next volume District and Circle (2006) won the T.S. Eliot Prize, the most prestigious poetry award in the UK. Commenting on the volume for the New York Times, critic Brad Leithauser found it remarkably consistent with the rest of Heaney’s oeuvre. But while Heaney’s career may demonstrate an “of-a-pieceness” not common in poetry, Leithauser found that Heaney’s voice still “carries the authenticity and believability of the plainspoken—even though (herein his magic) his words are anything but plainspoken. His stanzas are dense echo chambers of contending nuances and ricocheting sounds. And his is the gift of saying something extraordinary while, line by line, conveying a sense that this is something an ordinary person might actually say.”

Heaney’s prose constitutes an important part of his work. Heaney often used prose to address concerns taken up obliquely in his poetry. In The Redress of Poetry (1995),according to James Longenbach in the Nation, "Heaney wants to think of poetry not only as something that intervenes in the world, redressing or correcting imbalances, but also as something that must be redressed—re-established, celebrated as itself." The book contains a selection of lectures the poet delivered at Oxford University as Professor of Poetry. Heaney's Finders Keepers: Selected Prose, 1971-2001 (2002) earned the Truman Capote Award for Literary Criticism, the largest annual prize for literary criticism in the English language. John Carey in the London Sunday Timesproposed that Heaney's "is not just another book of literary criticism…It is a record of Seamus Heaney's thirty-year struggle with the demon of doubt. The questions that afflict him are basic. What is the good of poetry? How can it contribute to society? Is it worth the dedication it demands?" Heaney himself described his essays as "testimonies to the fact that poets themselves are finders and keepers, that their vocation is to look after art and life by being discoverers and custodians of the unlooked for."

As a translator, Heaney’s most famous work is the translation of the epic Anglo-Saxon poem Beowulf (2000). Considered groundbreaking because of the freedom he took in using modern language, the book is largely credited with revitalizing what had become something of a tired chestnut in the literary world. Malcolm Jones inNewsweek stated: "Heaney's own poetic vernacular—muscular language so rich with the tones and smell of earth that you almost expect to find a few crumbs of dirt clinging to his lines—is the perfect match for the Beowulf poet's Anglo-Saxon…As retooled by Heaney, Beowulf should easily be good for another millennium." Though he has also translated Sophocles, Heaney remains most adept with medieval works. He translated Robert Henryson’s Middle Scots classic and follow-up to Chaucer, The Testament of Cresseid and Seven Fables in 2009.

In 2009, Seamus Heaney turned 70. A true event in the poetry world, Ireland marked the occasion with a 12-hour broadcast of archived Heaney recordings. It was also announced that two-thirds of the poetry collections sold in the UK the previous year had been Heaney titles. Such popularity was almost unheard of in the world of contemporary poetry, and yet Heaney’s voice is unabashedly grounded in tradition. Heaney’s belief in the power of art and poetry, regardless of technological change or economic collapse, offers hope in the face of an increasingly uncertain future. Asked about the value of poetry in times of crisis, Heaney answered it is precisely at such moments that people realize they need more to live than economics: “If poetry and the arts do anything,” he said, “they can fortify your inner life, your inwardness."

(Author of introduction) Thomas Flanagan, There You Are: Writing on Irish and American Literature and History, edited by Christopher Cahill, New York Review Books, 2003.

(Translator) The Burial at Thebes: A Version of Sophocles' "Antigone," Farrar, Straus (New York, NY), 2004.

(Translator) The Testament of Cresseid, Enitharmon Press, 2004.

(Translator) Columcille the Scribe, The Royal Irish Academy, 2004.

(Translator) The Testament of Cresseid and Seven Fables, Faber and Faber, 2009.

Contributor to books, including The Writers: A Sense of Ireland, O'Brien Press (Dublin, Ireland), 1979; Canopy: A Work for Voice and Light in Harvard Yard, Harvard University Art Museums, 1997; Healing Power: The Epic Poise—A Celebration of Ted Hughes, edited by Nick Gammage, Faber, 1999; For the Love of Ireland: A Literary Companion for Readers and Travelers, Ballantine, 2001; 101 Poems against War, edited by Matthew Hollis and Paul Keegan, Faber, 2003; and Don't Ask Me What I Mean: Poets in Their Own Words, Picador, 2003. Contributor of poetry and essays to periodicals, including New Statesman, Listener, Guardian, Times Literary Supplement,and London Review of Books. Heaney's papers and letters are collected at Emory University, Atlanta, GA.

Time, March 19, 1984; February 25, 1985; October 16, 1995; March 20, 2000, Paul Gray, "There Be Dragons: Seamus Heaney's Stirring Translation of Beowulf Makes Waves on Both Shores of the Atlantic," p. 84.